ATTINY4_1 Datasheet, PDF (106/168 Pages) ATMEL Corporation – 8-bit Microcontroller with 512/1024 Bytes In-System Programmable Flash

• Bits 2:0 – GT[2:0]: Guard Time
These bits specify the number of additional IDLE bits that are inserted to the idle time when
changing from reception mode to transmission mode. Additional delays are not inserted when
changing from transmission mode to reception.
The total idle time when changing from reception to transmission mode is Guard Time plus two
IDLE bits. Table 14-13 shows the available Guard Time settings.
Table 14-13. Guard Time Settings
GT2
GT1
GT0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Guard Time (Number of IDLE bits)
+128 (default value)
+64
+32
+16
+8
+4
+2
+0
The default Guard Time is 128 IDLE bits. To speed up the communication, the Guard Time
should be set to the shortest safe value.
14.7.3 TPISR – Tiny Programming Interface Status Register
Bit
7
6
5
4
3
2
1
0
CSS: 0x00
–
–
–
–
–
–
NVMEN
–
TPIPCR
Read/Write
R
R
R
R
R
R
R/W
R
Initial Value
0
0
0
0
0
0
0
0
• Bits 7:2, 0 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 1 – NVMEN: Non-Volatile Memory Programming Enabled
NVM programming is enabled when this bit is set. The external programmer can poll this bit to
verify the interface has been successfully enabled.
NVM programming is disabled by writing this bit to zero.
106 ATtiny4/5/9/10
8127C–AVR–10/09